Antifungals Flashcards

1
Q

Classification of Mycoses

A

System (potentialy life threatening)

Superficial

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2
Q

Antifungal Targets

A

Targets:
membranes (ergosterol)
nucleic acids
cell wall

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3
Q

Drugs for systemic fungal infections

A

Amphotericin B
Flucytoisne
Imidazoles (fluconazole, itraconazole, voriconazole)
Capsofungin

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4
Q

Amphotericin B

A

Effective for most serious systemic mycoses especially those are life threatening immediately
Gold standard for anti-fungal effectiveness by which other drugs are judged
Side effects: so use for proven of highly suspected systemic infections (Total cumulative dose is important for reasons permanent renal toxicity)
fever, nausea, vomiting, headache, chills, hypotension, hypokalemia, tachypnea, 90% with nonpermanent nephrotoxicity (permanent renal damage occurs depending of total dose), reversible hypochromic, normocytic anemia
Only fungistatic at serum levels in human

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5
Q

MOA Amphotericin B

A

Binds to ergosterol in membrane causes membrane leakiness (causes holes)

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6
Q

Flucytosine (5-FC)

A

Serious infections: Candida, Cryptococcus
Used in conjunction (synergistic) with amphotericin B
Side effects: nausea, vomiting, diarrhea, enterocolitis, Leukopnia thrombocytopenia, extreme caution with renal insufficiency or bone marrow depression, reversible elevated hepatic enzymes

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7
Q

Fluctyosine (5-FC)

A

fungal cytosine deaminase which converts cytosine permease to 5 FU
which inhibits DNA synthesis

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8
Q

Triazoles

A

fluconazole
voriconazole
itraconazole

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9
Q

Triazole MoA and Side effects

A

Inhibit 14 alpha sterol demethylase, fungal cytochrome P450 that converts lanosterol to erosterol
Net effect is inhibition of ergosterol synthesis
This is slower onset mechanism
Side effects: nausea, vomiting, rash, diarrhea, headache, mild hepatotoxicity (discontinue with onset of liver dysfunction)
Inhibits metabolism of several other drugs (CYP3A and 2C families) because inhibit CYP450s

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10
Q

Fluconazole

A

Cryptococcus
Candida (many sites including CNS and urinary)
most C. albicans, some C. glabrata, not C. krusei (narrow spectrum of Candida)
CNS penetration: yes
Active drug in urine
Lowest incidence of hepatotoxicity among the azole antifungals

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11
Q

Itraconazole

A

Blastomyces
Histoplasma
Candia (esophagus and oropharynx but not CNS and urinary)
More albicans and glabrata and some C. krusei
No CNS penetration or active drug in urine
Contraindications: do not give with other drugs that are metabolized by CYP3A4
can cause potential for severe CV events including death

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12
Q

Voriconazole

A

Aspergillus
Candida (not urinary)
covers many species including glabrata and krusei
Limited CNS penetration and no active drug in urine
Side effects: visual distrubances (30%), phosensitive component to rash

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13
Q

Anti-fungals that Target Cell Wall

A

caspofungin

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14
Q

Caspofungin

A

Treat invasive Aspergillus (intolerant to other drugs), Candida (esophageal and systemic and broad coverage of glabra and krusei)
MOA: inhibit fungal cell wall synthesis by noncompeitively blocking synthesis of B(1,3)-D-glucan in filamentous fungi
No cross resistance with imidazoles and triazoles
Side effects: fever, nausea, flushing, phlebitis at injection site

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15
Q

Treatment of Superficial Mycoses

A

Nystatin
Imidazoles (fluconazole, miconazole, clotrimazole, itraconazole)
Opthalmic : natamycin

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16
Q

Fluconazole

A
Candida infections (vaginal, urinary track, oropharynx)
Oral not topical
17
Q

Miconazole

A

Topical: creams/suppositories for vaginal Candida

18
Q

Clotrimazole

A
Candia
topical use (oral troches or vaginal creams/solutions)
Side effect or oral troches: abnormal liver function test
19
Q

Itraconazole

A

Candida: oropharyngeal and esophageal (oral not topical)

20
Q

Nystatin

A

Mechanism similar to amphotericin B (effecitve against -azole-resistant strains)
Topical use for Candida (skin, mucous membrane, vaginal)
Oral use for GI tract Candida (not absorbed systemically)
Side effects: oral has GI distress and bad taste

21
Q

Amphotericin B

A

Topical

Cutaneous or mucosal Candida (not for dermatophytes

22
Q

Treatment of Opthalmic fungal infections

A

Natamycin- opthalmic infections
Mechanism similar to amphotericin B
not systemically because too toxic
toxicity: conjunctival chemosis and hyperemia

23
Q

Topical Treatment for Dermatophytes (Tinea pedis, Tinea cruris, Tinea corporis)

A

Miconazole, clotrimazole
Tolnaftate
Terbinafine
Ciclopirox (nail laquer)

24
Q

Topical Treatment for Fungal Nail Infections

A

Ciclopirox- FDA approved topical for mld to moderate fungal nail infections
mechanism: inhibit metal dependent fungal enzymes by metal chelation

25
Terbinafine
Oral drugs 12 week therapy for nail infections deposit and stay in tissue for a long time also shorter duration of therapy for tinea capitis MOA: blocks early in pathway from blocking squalene to 2,3-oxidosqualene upstream of ergosterol and fungicidal because squalene accumulates and disrupt fungal cell membrane Side effects: diarrhea, dyspepsia, abdominal pain
26
Griseofulvin
for recalcitrant dermatophytic infections of skin, hair, nails Therapy for tinea capitis Mechanism: interfere with microtubule function/mitotic spindle/mitosis Side effects: contraindicated in those with prophyria and advanced liver disease, inreased metabolism of several drugs (CYP inducer), Use with caution with those with penicillin allergies
27
Itraconazole
Oral therapy for fungal toenail infections Side effects: nausea, vomiting, rash, diarrhea, headache, edema, inhibits metabolism of many drugs, discontinue if signs of liver dysfunction
28
Oral Antifungal dermatophytes
Itraconazole Griseofulvin Terbinafine